Medical film gloves are utilized by laboratory workers and physicians to reduce the incidence of contact transmission of various contaminants. Medical gloves should be relatively thin so that tactile sensation is not lost, however, the gloves must also be strong to resist rupture. Also, because the surfaces of film gloves tend to adhere to each other when packaged and to the user's hand while donning, the glove surfaces should have some form of lubricious property.
Conventional medical glove manufacturers typically utilize donning powders, such as corn starch or talc, over the surfaces of the glove to overcome the foregoing problems. Donning powders function as a lubricant by separating the glove surfaces to prevent self-adherence and to allow the glove surfaces to slide over a user's hand by reducing the friction between the glove and skin surfaces.
However, donning powders can also contaminate wounds, irritate skin, leave a residue on equipment and clothing, and mechanically interfere with some medical procedures. Powderfree gloves have been identified as a solution to many of the foregoing problems.
To render gloves powderfree, present methods utilize two basic friction reduction systems or a combination thereof. The first is replacing the powder with another lubricant and the second is imparting a contact-reducing texture to the hand-contacting surface of the glove. Commonly used lubricants include silicone oil, fatty acids, and surfactants. Lubricants, as well as gels and emollients, can have many of the same problems seen with powders. Thus, it is desirable to impart a lubricious feature to a glove without the use of lubricants or the like.
The present invention is directed to a powderfree glove having a contact-reducing texture formed on the hand-contacting surface of the glove. Present methods employed to impart this texture to a glove include hardening the glove surface to reduce friction with the user's skin and forming a textured coating over the base layer. However, problems encountered with hardened glove surfaces include reduction of mechanical performance, leading to greater incidence of cracks or breaks in the glove, and reduced sensitivity. In a multi-layered glove, the hardened layer can separate from adjoining layers during stripping from the glove former, donning by the user, or in use during flexure. This can result in tears in the adjoining layers.
More promising powderfree gloves comprise a textured coating formed over the base layer, such as the glove of U.S. Pat. No. 4,143,109, wherein Stockum teaches a coated glove having solid particles protruding from the coating to impart texture thereto, which reduces friction with the skin of the user during donning. However, the exposed solid particles can dislodge from the glove coating, thus failing the requirements of a powderfree glove. Another problem with coated gloves is conforming the relative elongation properties of the adjoining layers. Otherwise, the layers can separate or rupture during stripping, donning, or use. For example, because latex has a high degree of elasticity, any coating formed thereon often must have low modulus of elasticity. As used herein, the term "modulus" refers to how a material deforms under stress (force). A low modulus glove is softer and requires less force to deform whereas a relatively higher modulus glove is harder and requires more force to deform. In U.S. Pat. No. 5,534,350, Liou suggests that a minimum elongation of 500% is preferred to assure that the secondary coating will flex with the underlying latex glove. In the case of a vinyl glove, the glove will not have sufficient strength to overcome high stripping forces due to a high coefficient of friction. As a result, high stripping forces induce unacceptable distortion or complete failure of a vinyl product.
The principal method for applying coatings to gloves is through the process of dipping. Typically, a glove former is heated and dipped into a dip tank having the desired constituents (e.g. latex or vinyl, plasticizers, etc.) in liquid form, removed and drained to the desired film thickness, and heated in an oven to fuse (or vulcanize, cure, cross-link, etc.) the materials and form the glove. If subsequent layers are to be applied, the above process is repeated the number of times corresponding to the number of additional layers desired. In high speed manufacturing processes, or where the composition of the layers differs, additional dip tanks are typically required. For efficient manufacture, the steps must occur in rapid succession with the time for each step minimized. Once the final layer is formed, the glove former is cooled, a cuff can be formed on the glove, and the glove is stripped from the glove former and collected for packaging.
There have been suggestions in the prior art that coatings can be applied by spraying, after which, the glove former is heated in an oven to fuse (vulcanize, cure, cross-link, etc.) the sprayed coating. However, the prior art teaches the purpose of these spray coatings is to form a continuous film layer equivalent to that of a dipped product.
The prior art does not suggest using spray deposition methods to impart texture, nor does it suggest any advantage of a coating that is intermittent instead of continuous, which is the focus of the present invention.